On 23/06/16 13:13, Manjeet Pawar wrote:
From: Rohit Thapliyal <r.thapliyal@xxxxxxxxxxx>
swiotlb default size of 64M is too big as
default value therefore it is made configurable
through command line through swiotlb_size parameter.
swiotlb allocation shall be done only when the
swiotlb size is given through command line.
Otherwise no swiotlb is allocated.
So all platforms with most memory physically above 4GB (which is quite a
lot of them) are suddenly broken unless they go and muck about with
their bootloader?
If anyone's got to muck about with their bootloader, why can't it be the
memory-constrained platforms just passing "swiotlb=1" instead?
Robin.
Signed-off-by: Rohit Thapliyal <r.thapliyal@xxxxxxxxxxx>
Signed-off-by: Manjeet Pawar <manjeet.p@xxxxxxxxxxx>
Reviewed-by: Akhilesh Kumar <akhilesh.k@xxxxxxxxxxx>
Reviewed-by: Ajeet Kumar Yadav <ajeet.y@xxxxxxxxxxx>
---
Documentation/kernel-parameters.txt | 3 +++
arch/arm64/mm/init.c | 3 ++-
include/linux/swiotlb.h | 1 +
lib/swiotlb.c | 33 +++++++++++++++++++++++++++++----
4 files changed, 35 insertions(+), 5 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 82b42c9..12b680f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3875,6 +3875,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
force -- force using of bounce buffers even if they
wouldn't be automatically used by the kernel
+ swiotlb_sz= [KNL] enter swiotlb size.
+ Sets the swiotlb size for eg. swiotlb_sz=64M
+
switches= [HW,M68k]
sysfs.deprecated=0|1 [KNL]
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index d45f862..89c6b39 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -403,7 +403,8 @@ static void __init free_unused_memmap(void)
*/
void __init mem_init(void)
{
- swiotlb_init(1);
+ if (swiotlb_enabled)
+ swiotlb_init(1);
set_max_mapnr(pfn_to_page(max_pfn) - mem_map);
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 017fced..c7eb146 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -11,6 +11,7 @@ struct page;
struct scatterlist;
extern int swiotlb_force;
+extern int swiotlb_enabled;
/*
* Maximum allowable number of contiguous slabs to map,
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 76f29ec..e89296a 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -54,6 +54,7 @@
#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
int swiotlb_force;
+int swiotlb_enabled;
/*
* Used to do a quick range check in swiotlb_tbl_unmap_single and
@@ -96,6 +97,9 @@ static DEFINE_SPINLOCK(io_tlb_lock);
static int late_alloc;
+unsigned long swiotlb_sz;
+unsigned int swiotlb_sz_shift;
+
static int __init
setup_io_tlb_npages(char *str)
{
@@ -112,6 +116,24 @@ setup_io_tlb_npages(char *str)
return 0;
}
early_param("swiotlb", setup_io_tlb_npages);
+
+static int __init
+setup_io_tlb_size(char *str)
+{
+ int len = strlen(str);
+
+ if (str[len-1] == 'M')
+ swiotlb_sz_shift = 20;
+ else if (str[len-1] == 'K')
+ swiotlb_sz_shift = 10;
+ str[len-1] = '\0';
+ if (isdigit(*str))
+ swiotlb_sz = kstrtoul(str, &str, 0);
+
+ swiotlb_enabled = 1;
+ return 0;
+}
+early_param("swiotlb_sz", setup_io_tlb_size);
/* make io_tlb_overflow tunable too? */
unsigned long swiotlb_nr_tbl(void)
@@ -120,8 +142,9 @@ unsigned long swiotlb_nr_tbl(void)
}
EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
-/* default to 64MB */
-#define IO_TLB_DEFAULT_SIZE (64UL<<20)
+/* Pass from command line as swiotlb_sz=64M (for eg.)*/
+#define IO_TLB_DEFAULT_SIZE (swiotlb_sz<<swiotlb_sz_shift)
+
unsigned long swiotlb_size_or_default(void)
{
unsigned long size;
@@ -153,10 +176,12 @@ void swiotlb_print_info(void)
vstart = phys_to_virt(io_tlb_start);
vend = phys_to_virt(io_tlb_end);
- printk(KERN_INFO "software IO TLB [mem %#010llx-%#010llx] (%luMB) mapped at [%p-%p]\n",
+ pr_info("software IO TLB [mem %#010llx-%#010llx] (%lu%cB) mapped at [%p-%p]\n",
(unsigned long long)io_tlb_start,
(unsigned long long)io_tlb_end,
- bytes >> 20, vstart, vend - 1);
+ bytes >> swiotlb_sz_shift,
+ swiotlb_sz_shift == 20 ? 'M' : 'K',
+ vstart, vend - 1);
}
int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
--
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